Buying a bicycle can be a quite an expenditure indeed. But you can also see it as an investment. In the long run a bicycle can save you money. By not taking the car or public transport for shorter distances you can save money in the long run.
And it is even better for your health too; another plus!

Sometimes it is better to save up some more so you can buy the bicycle you really want instead of a cheaper one.

Good luck with your choices!